Conventionally, there is a PET (Positron Emission Tomography) apparatus as this type of nuclear medicine diagnostic apparatus, i.e. ECT (Emission Computed Tomography). The PET apparatus is constructed to reconstruct a tomographic image of an inspection object only when two detectors coincidentally detect two gamma rays generated by annihilation of positrons. Specifically, the inspection object is medicated with a radioactive drug including a positron-emitting radionuclide. The detectors, which include detector element groups constructed of numerous scintillators, for example, detect pair annihilation gamma rays of 511 keV released from the medicated inspection object. And when two detectors detect gamma rays within a certain period of time, it is regarded as a “coincident” detection, and is counted as a pair of pair annihilation gamma rays. Further, a generating position of the pair annihilation gamma rays is determined to be on a straight line linking the two detectors having detected them. Such coincidence information is accumulated and reconstruction processing is carried out to obtain a positron-emitting radionuclide distribution image, i.e. a tomographic image.
Such a PET apparatus generally is constructed by arranging a plurality of detectors in a circle to surround an inspection object for improvement in sensitivity. In the case of a site-specific PET apparatus for imaging parts of the inspection object such as the breasts, it is constructed to surround only the site to be imaged. Consequently, with a plurality of detectors arranged adjacent the site to be imaged, detection sensitivity can be further improved (see Japanese Unexamined Patent Publication No. 2009-30031, for example).
As shown in FIG. 11 (a) or FIG. 11 (b), a mammo-PET apparatus 101 for imaging the breasts of an inspection object has a support unit 102 on which the inspection object M is placed in a prone position (face-down state). A supporting surface 103 of the support unit 102 has an opening 104 formed therein to receive a breast b for diagnosing the breasts b below the supporting surface 103. A detector ring 106 is disposed inside the support unit 102 for detecting gamma rays generated from the inspection object M, the detector ring 106 (a plurality of gamma-ray detectors 107) being arranged to surround the breast b inserted in the opening 104. A mat 120 serving as a cushion is laid on the supporting surface 103 of the support unit 102 (see Japanese Unexamined Patent Publication No. 2008-232913, for example).
There is the following as an apparatus which images the breasts of an inspection object (see Japanese Unexamined Patent Publication No. 2009-189726, for example). As shown in FIG. 12, this apparatus has a bed 201 for supporting an inspection object M in a prone position. This bed 201 has a hemispherical vessel 202 attached thereto for surrounding a breast b of the inspection object M, and a measuring unit 203 is provided for the vessel 202. Mounted on a base 204 of the bed 201 are a chest supporting plate 205, a mat 206 and a pillow 207. The chest supporting plate 205 is formed of a plate-like member for supporting the chest of the inspection object M. The mat 206 is formed of a soft material for supporting a portion from the abdomen to the legs of the inspection object M. A portion of an upper surface of the mat 206 which supports the knees of the inspection object M is lower than the other portions, to ease a burden when the inspection object M takes a position for a time of measurement. The pillow 207 supports the head of the inspection object M, is formed of a soft member, and is mounted on the base 204 through a height adjusting mechanism 208
[Patent Document 1]
Unexamined Patent Publication No. 2009-300319
[Patent Document 2]
Unexamined Patent Publication No. 2008-232913
[Patent Document 3]
Unexamined Patent Publication No. 2009-189726